The present invention relates to methods for convolutely lining and wrapping tubes with protective materials such as metal foils and the tubes prepared by these methods.
Tubular structures have a multitude of applications in a variety of industries as support trusses, piping systems and fluid containers. Certain composite tubular structures are used in applications where environmental factors such as heat, moisture, chemicals, radiation, particle impact and the like can have an adverse effect on the materials imparting structural integrity to the tubular structure. For instance, in order to protect tubular trusses used in the construction of low earth orbit space stations, it is desirable to line and/or wrap the tubular truss with a material that will isolate the underlying materials from low earth orbit environmental conditions, such as atomic oxygen, charged particle radiation, ultraviolet radiation, micrometeoroids and space debris, as well as to prevent moisture absorption/desorption of the tubular truss and provide a passive thermal control coating. Also, by lining and/or wrapping tubular structures, increased strength and rigidity can be imparted to the tubular structure. In other applications that are less technologically oriented, it is desirable to line or wrap tubular structures for aesthetic and decorative purposes.
When lining a tubular structure with a resilient lining material, it is often difficult to fix the lining material in a stationary position as the tubular structure is formed around the lining material. Although resilient lining materials can be formed when subjected to pressure, the resiliency of the material causes it to return to its original shape when the pressure is removed. The inability to fix the lining material often prevents its use or results in a tubular structure that has an uneven or discontinuous lining. These uneven or discontinuous linings do not provide the protective layer that would otherwise be present if the lining material were even and continuous.
Because the exterior of a tubular structure is often exposed to environmental conditions, it is often advantageous to protect the exterior of the tubular structure by wrapping it with a protective material. In order to ensure effective protection of the underlying tubular structure, it is important that the seam that seals the wrapping material to itself be such that it is not susceptible to degradation upon exposure to environmental conditions. Otherwise, the underlying tubular structure may become exposed to the adverse environmental conditions as a result of the failure of the seal. For example, in the specific application of tubular trusses used in the construction of space stations, epoxy resins that are generally used as adhesives are susceptible to degradation by the atomic oxygen environment present in low earth orbital space. After extended exposure to atomic oxygen, the epoxy resin bond begins to decompose and as a consequence the underlying tubular structure is no longer isolated from the low earth orbital environmental conditions.
It has been discovered that the method of the present invention provides uniformly lined tubes that do not suffer from the problems associated with tubes that are lined by conventional means. The lining provides a protective layer that is free of flaws or dicontinuities that could result in the underlying tubular structure being exposed to undesirable environmental factors. The method also provides a wrapped tubular structure that is sealed in a manner that will not result in the failure of the seal, followed by degradation of the underlying tubular structure. The method is economical and does not require complex processing steps or equipment.